I.A. Navrotsky, A.A. Burtsev

One of the options for creation of electron-optical systems is multiple-tip field-emission cathode with a grid, in which the diameters of openings exceed the period of tips in tens of times. To make a field more uniform on the cathode, it is offered to change the enhancement factor of a field on the tip apexes by a change of the tip density on a cathode surface, i.e. a period between tips. Estimates show that at the irregular density of tips of array multiple-tip structure, the increase of the structure period from the edge of the cathode to its center allows to increase a field-emission current approximately up to 30 % in comparison with the case of a constant value of density N = const. Basing on the software «Lorentz» and taking into account a start points of charged particles on a cathode microstructure with a changing period, a three-dimensional computer modelling of an electronic gun based on multiple-tip cathodes with a compression of an electron flow is carried out.